The invention relates to an apparatus for actuating the flaps and/or slats of an aircraft, using a control command transducer embodied as a lever mechanism for generating the desired or specified commands for an adjustment of the flaps and/or slats.
Conventional transport aircraft are equipped with a control command transducer arrangement for actuating the flaps and/or slats of the aircraft. The arrangement typically includes a flap/slat command input lever mounted on the instrument panel or a console in the cockpit, for the pilot to select the desired flap/slat settings by sliding or pivoting the lever to the desired position corresponding to the desired flap/slat setting. A sensor arrangement is coupled to the command input lever and generates electrical sensor signals responsive to and dependent on the position of the command input lever. These sensor signals are provided to at least one control computer, which in turn responsively generates actuator signals that are provided to actuators for correspondingly actuating the flaps and/or slats to the commanded settings. The lever arrangement thus embodies a control command transducer that has only a singular mechanical command transmission path of the lever adjustments corresponding to the command inputs for adjusting the flaps and/or slats.
The conventional lever mechanism includes a control coulisse or control slide guide slot arrangement with a specified number of catches, that define the positions to which the command input lever can be moved and then fixed, so as to specify the corresponding allocated flap/slat setting. Furthermore, blocking means embodied as a baffle plate prevent the lever from being moved in a single continuous adjustment through its entire adjustment range, e.g. from the zero setting to the full extended setting, or vice versa, without stopping in the intermediate positions or settings.
The conventional control command transducer arrangements as described suffer disadvantages arising from the provision of only a singular mechanical command transmission path, including a single lever mechanism and a single sensor arrangement. In the event of the failure of this singular lever mechanism or sensor arrangement, for example due to fracture of any of the components, or due to mechanical jamming at any point within the single command transmission path or within the sensor arrangement, then the entire slat and landing flap system can no longer be actuated.
In order to avoid the dependence of the entire system on the operability of only a single command transducer arrangement, an alternative control switch could additionally be provided. In other words, a separate backup system could be provided to achieve safety redundancy. This, however, would require the installation of additional switches in the cockpit, and would also require special procedures for the pilots to follow to switch over from the normal command transducer arrangement to the backup system in the event of the malfunction or non-operability of the normal command transducer arrangement.
In view of the above, it is an object of the invention to provide an arrangement of the general type described above, which is further developed and improved, however, so that a mechanical rupture or jamming of a single mechanical command transmission path, or a failure of a single sensor arrangement, will not lead to a loss of the landing flap and slat actuation command function. Another object of the invention is to avoid the need for special procedures to be followed by the pilots in the event of a jamming or other malfunction of a single command transmission path. The invention further aims to avoid or overcome the disadvantages of the prior art, and to achieve additional advantages, as apparent from the present specification.
The above objects have been achieved according to the invention in an apparatus for actuating at least one of the slats and landing flaps on a wing of an aircraft, including double lever mechanisms forming a control command transducer for inputting desired adjustment commands for adjusting at least one of the slats and landing flaps. The two lever mechanisms are independent of each other in their layout and construction, but are coupled to each other in their function, and thereby form two functionally coupled command transmission paths. Each lever mechanism comprises a respective command input lever (also called an adjusting or actuating lever) and a respective linkage mechanically connecting the lever to a respective one of two rotatable sensor disks so as to apply the pivoting lever motion of the lever to a pivoting rotational motion of the disk. Each sensor disk cooperates with a respective group of plural signal emitters (e.g. electrical or optical signal emitters), which are conductively connected (e.g. by wires or optical fiber cables) to a respective one of two control computers. Responsive to the signals provided by the signal emitters, the computers in turn generate and transmit actuating signals (e.g. electrical or optical signals) to actuators connected to the respective slat or landing flap for actuating the same. In this context, the two lever mechanisms are functionally coupled and combined with each other to form a single control command transducer arrangement.
Thus, according to the invention, the lever mechanism is carried out in a double configuration, and is divided into two command transmission paths that are respectively independent from each other in their layout and construction, but are coupled to each other in their function. More particularly, two adjusting levers and two linkages are functionally combined to form a single control command transducer arrangement. Furthermore, the signal emitters of a respective sensor disk associated with a respective one of the linkages and adjusting levers are electrically connected to a respective one of the two control computers. This provides a parallel yet interconnected redundancy of the mechanical command transmission path, the sensor arrangement or signal conversion function, and the signal processing and flap or slat actuation.
According to further structural features of the invention, the adjusting levers (i.e. the command input levers) are respectively guided in a blockage-free sliding guide arrangement, having a guide slot with detent recesses on one side thereof and baffle protrusions on the other side thereof. A spring-loaded detent catch member engages into any selected one of the detent recesses to fix the adjusting lever at a selected detented position. The baffle protrusions prevent a full range adjustment of the adjusting lever without intermediate stops in the detented positions. Further preferably, the sliding guide arrangement is enclosed in a housing so it is protected from jamming by foreign objects or contaminants, and the adjusting lever travel slot through which the lever passes into the housing is covered by a mechanical movable cover in the form of a rolling or lamellar door, an accordion-like bellows, or a movable sheet metal or plastic sliding cover. With such an arrangement, any loose or broken-off pieces of the arrangement cannot cause a blockage of the mechanism. Furthermore, foreign bodies or contaminants cannot penetrate into the guide slot of the sliding guide arrangement, which further prevents the occurrence of blockages.
With the inventive apparatus, even if one of the adjusting levers and/or one of the linkages and/or one of the sensor disks fails or becomes blocked or jammed, the slat or flap command functions can still be carried out by the continuing operation of the other lever, linkage, and/or sensor disk. There is no need for the pilot to switch over from a primary system to a backup system. With the doubled lever mechanism, the transmission and conversion and processing functions will all remain effective, because the second command input path through the second adjusting lever, the second linkage, and the second sensor disk will remain fully functional even in the event of a mechanical disconnect, failure, or blockage of any component of the first command transmission path.
More particularly, the probability of a total failure of the control command transducer arrangement for the redundant control computers can be reduced to  less than 10xe2x88x929/Fh (flight hour). Namely, for a complete failure of the command signal transducer arrangement, both lever mechanisms would have to fail, because the inventive arrangement provides two redundant adjusting levers that are preferably functionally coupled or combined to functionally form one redundant operating lever, by means of mechanical synchronization or coupling of the two levers, for example by means of bolts, screws, rivets, or the like, or by means of a xe2x80x9clever within a leverxe2x80x9d arrangement of the two levers. The coupling can be designed so that it can be overcome (e.g. by shearing of a mechanical coupling or by slipping of a frictional coupling) by an increased adjusting force being manually applied to one of the adjusting levers. Thereby, if one of the levers or linkages should become jammed, then the other lever and linkage can still be used normally to carry out the command functions simply by initially pushing the unjammed lever hard enough to decouple it from its normal detent gate. A mechanical rupture of one command path, or the complete failure of one sensor arrangement, will not lead to the loss of the slat or landing flap command function, because the second non-faulty path will continue to carry out the proper lever function including transmission of the valid adjusting commands through the remaining non-faulty sensor arrangement.
Furthermore, the invention achieves the advantage of avoiding the need of additional cockpit switches and required alternative cockpit procedures for activating a backup system. By avoiding the need for an alternative operating button, it becomes possible to achieve a significant simplification of the system design and layout, for example relating to the computer processor functionalities as well as the cockpit interface, and it becomes possible to maintain previous operating procedures, in an advantageous manner.